diff options
Diffstat (limited to 'chapter09/symlinks.xml')
| -rw-r--r-- | chapter09/symlinks.xml | 46 |
1 files changed, 22 insertions, 24 deletions
diff --git a/chapter09/symlinks.xml b/chapter09/symlinks.xml index 951e6976d..3b46a67b0 100644 --- a/chapter09/symlinks.xml +++ b/chapter09/symlinks.xml @@ -21,7 +21,7 @@ discovered. For example, on a computer having two network cards made by Intel and Realtek, the network card manufactured by Intel may become eth0 and the Realtek card becomes eth1. In some cases, after a reboot the cards - get renumbered the other way around.</para> + could get renumbered the other way around.</para> <para>In the new naming scheme, typical network device names would then be something like enp5s0 or wlp3s0. If this naming convention is not @@ -44,7 +44,7 @@ <sect3> <title>Creating Custom Udev Rules</title> - <para>The naming scheme can be customized by creating custom Udev + <para>The naming scheme can be customized by creating custom udev rules. A script has been included that generates the initial rules. Generate these rules by running:</para> @@ -68,24 +68,24 @@ along with its driver in parentheses, if the driver can be found. Neither the hardware ID nor the driver is used to determine which name to give an interface; this information is only for reference. The second line is the - Udev rule that matches this NIC and actually assigns it a name.</para> + udev rule that matches this NIC and actually assigns it a name.</para> - <para>All Udev rules are made up of several keys, separated by commas and + <para>All udev rules are made up of several keys, separated by commas and optional whitespace. This rule's keys and an explanation of each of them are as follows:</para> <itemizedlist> <listitem> - <para><literal>SUBSYSTEM=="net"</literal> - This tells Udev to ignore + <para><literal>SUBSYSTEM=="net"</literal> - This tells udev to ignore devices that are not network cards.</para> </listitem> <listitem> - <para><literal>ACTION=="add"</literal> - This tells Udev to ignore this + <para><literal>ACTION=="add"</literal> - This tells udev to ignore this rule for a uevent that isn't an add ("remove" and "change" uevents also happen, but don't need to rename network interfaces).</para> </listitem> <listitem> - <para><literal>DRIVERS=="?*"</literal> - This exists so that Udev will + <para><literal>DRIVERS=="?*"</literal> - This exists so that udev will ignore VLAN or bridge sub-interfaces (because these sub-interfaces do not have drivers). These sub-interfaces are skipped because the name that would be assigned would collide with their parent devices.</para> @@ -96,14 +96,14 @@ </listitem> <listitem> <para><literal>ATTR{type}=="1"</literal> - This ensures the rule only - matches the primary interface in the case of certain wireless drivers, + matches the primary interface in the case of certain wireless drivers which create multiple virtual interfaces. The secondary interfaces are skipped for the same reason that VLAN and bridge sub-interfaces are skipped: there would be a name collision otherwise.</para> </listitem> <listitem> <para><literal>NAME</literal> - The value of this key is the name that - Udev will assign to this interface.</para> + udev will assign to this interface.</para> </listitem> </itemizedlist> @@ -133,8 +133,8 @@ default for USB and FireWire devices), where the rules it creates depend on the physical path to the CD or DVD device. Second, it can operate in <quote>by-id</quote> mode (default for IDE and SCSI devices), where the - rules it creates depend on identification strings stored in the CD or DVD - device itself. The path is determined by Udev's <command>path_id</command> + rules it creates depend on identification strings stored on the CD or DVD + device itself. The path is determined by udev's <command>path_id</command> script, and the identification strings are read from the hardware by its <command>ata_id</command> or <command>scsi_id</command> programs, depending on which type of device you have.</para> @@ -159,11 +159,11 @@ <important><para>External devices (for example, a USB-connected CD drive) should not use by-path persistence, because each time the device is plugged into a new external port, its physical path will change. All - externally-connected devices will have this problem if you write Udev rules + externally-connected devices will have this problem if you write udev rules to recognize them by their physical path; the problem is not limited to CD and DVD drives.</para></important> - <para>If you wish to see the values that the Udev scripts will use, then + <para>If you wish to see the values that the udev scripts will use, then for the appropriate CD-ROM device, find the corresponding directory under <filename class="directory">/sys</filename> (e.g., this can be <filename class="directory">/sys/block/hdd</filename>) and @@ -182,18 +182,18 @@ as follows (where <replaceable>mode</replaceable> is one of <quote>by-id</quote> or <quote>by-path</quote>):</para> -<screen role="nodump"><userinput>sed -i -e 's/"write_cd_rules"/"write_cd_rules <replaceable>mode</replaceable>"/' \ - /etc/udev/rules.d/83-cdrom-symlinks.rules</userinput></screen> +<screen role="nodump"><userinput>sed -e 's/"write_cd_rules"/"write_cd_rules <replaceable>mode</replaceable>"/' \ + -i /etc/udev/rules.d/83-cdrom-symlinks.rules</userinput></screen> <para>Note that it is not necessary to create the rules files or symlinks - at this time, because you have bind-mounted the host's - <filename class="directory">/dev</filename> directory into the LFS system, + at this time because you have bind-mounted the host's + <filename class="directory">/dev</filename> directory into the LFS system and we assume the symlinks exist on the host. The rules and symlinks will be created the first time you boot your LFS system.</para> <para>However, if you have multiple CD-ROM devices, then the symlinks generated at that time may point to different devices than they point to on - your host, because devices are not discovered in a predictable order. The + your host because devices are not discovered in a predictable order. The assignments created when you first boot the LFS system will be stable, so this is only an issue if you need the symlinks on both systems to point to the same device. If you need that, then inspect (and possibly edit) the @@ -212,9 +212,9 @@ E.g., if you have a USB web camera and a TV tuner, sometimes <filename>/dev/video0</filename> refers to the camera and <filename>/dev/video1</filename> refers to the tuner, and sometimes - after a reboot the order changes to the opposite one. + after a reboot the order changes. For all classes of hardware except sound cards and network cards, this is - fixable by creating Udev rules for custom persistent symlinks. + fixable by creating udev rules for custom persistent symlinks. The case of network cards is covered separately in <xref linkend="ch-config-network"/>, and sound card configuration can be found in <ulink url="&blfs-book;postlfs/devices.html">BLFS</ulink>.</para> @@ -237,10 +237,8 @@ <screen role="nodump"><userinput>cat > /etc/udev/rules.d/83-duplicate_devs.rules << "EOF" <literal> # Persistent symlinks for webcam and tuner -KERNEL=="video*", ATTRS{idProduct}=="1910", ATTRS{idVendor}=="0d81", \ - SYMLINK+="webcam" -KERNEL=="video*", ATTRS{device}=="0x036f", ATTRS{vendor}=="0x109e", \ - SYMLINK+="tvtuner" +KERNEL=="video*", ATTRS{idProduct}=="1910", ATTRS{idVendor}=="0d81", SYMLINK+="webcam" +KERNEL=="video*", ATTRS{device}=="0x036f", ATTRS{vendor}=="0x109e", SYMLINK+="tvtuner" </literal> EOF</userinput></screen> |